This invention relates to the field of management and control of locomotives and trains, and discloses a unique system for monitoring conditions in any of a plurality of cars in a train. However, the invention can be used in other applications, as described below.
One of the problems in the operation of modern locomotives, especially in freight trains, is the difficulty in monitoring the amount of fuel remaining in the train. Freight trains typically include up to about six locomotives, coupled together at the front of the train, followed by up to several hundred cars. Each locomotive is self-contained, and includes its own fuel tank. In most train systems of the prior art, there has been no reliable and convenient means of measuring the amount of fuel in each tank. Even experienced train crews have been surprised to find their fuel tanks suddenly empty, midway between fueling terminals. This situation obviously results in great expense and inconvenience.
Most of the fuel gauges used on locomotives, in the prior art, have not been accessible to the train crew while the train is moving. Instead, locomotives of the prior art have been provided with sight glasses, which measure the top 1000 gallons of fuel in the tank. Some are equipped with float gauges, which can be read by an observer on the ground, while the train is stopped. These float gauges are notoriously inaccurate, and cannot be read from the walkways along the cab or from inside the cab. Hence, such gauges cannot be used while the train is moving. One example of a fuel gauge for locomotives, employing a gauge glass assembly, is shown in U.S. Pat. No. 4,454,759.
There have recently appeared several types of electronic fuel gauges for locomotives. These gauges employ a pressure sensor at the bottom of the fuel tank. The sensor produces a voltage which is transmitted along a cable to apparatus in the cab which converts the voltage to a meaningful display. The sensor can be a pressure transducer, of the type shown in U.S. Pat. Nos. 3,036,463, 3,054,292, or 3,726,140, or any other equivalent type. An example of the use of a microprocessor to interpret the data obtained from such transducers is shown in U.S. Pat. No. 4,386,406. In the latter patent, the microprocessor stores data on the relationship between the output of the correct amount of fuel. A somewhat similar scheme is employed in the computer-based fuel indicator described in U.S. Pat. No. 4,402,048.
Other examples of fuel monitoring systems which are useful in situations involving a plurality of tanks are shown in U.S. Pat. Nos. 3,958,107, 4,306,579, and 4,513,617. The latter patent deals with monitoring the state of the many tanks in a gasoline station. The former patents are concerned with monitoring the fuel tanks in an aircraft. All of the above-cited patents are incorporated by reference into this specification.
While some of the electronic gauges currently available enable the train crew to monitor fuel levels while the train is moving, none allows the monitoring of fuel levels in any locomotive where there are no crew members. Even with the electronic gauges described above, if the engineer needs to know whether a fuel stop is necessary, the train must be stopped, and the gauge in each locomotive must be checked individually.
The same considerations apply to the monitoring of parameters other than fuel quantity. For example, locomotives have a hopper for storing sand, which is sprayed onto the track when the train is started, to provide traction. The amount of sand in the hopper needs to be monitored. It is also desirable that the engineer know the level of air pressure in the air brakes for each locomotive. Oil levels and water levels are further examples of parameters to be observed.
The present invention provides a solution to the problem of monitoring parameters in a plurality of railroad locomotives or cars. The system of the present invention is easy to install, and easy to use. The system has the advantage that a plurality of identical components can be installed in a plurality of locomotives or cars, without regard to the order of the cars. The system compensates for whatever differences exist among locomotives, such as in the size and shape of the fuel tanks, by providing means for calibrating the particular components installed in a given locomotive.
When the system is used to monitor fuel quantity, the engineer can make informed decisions about whether and when to stop for refueling, thereby achieving significant savings in operating costs. But, as stated above, the system can be used to monitor other conditions in each locomotive of the train, without the necessity of leaving the lead locomotive.
While the invention is described mainly with respect to railroads, it is understood that the invention can also be used in other contexts, wherever it is necessary to monitor a parameter in a plurality of similar modules. Thus, the invention could be used to measure parameters in the tanks of an airplane, or to measure conditions in a plurality of buildings, or in a wide variety of other applications. The invention can be used with modules which are fixed, i.e. modules whose sequence is not easily changed, but it is especially useful with modules whose order is changed frequently, as is true in the case of a plurality of locomotives or railroad cars.